Abstract Factors, including co-morbidities, chronic inflammation, and immune activation are known to affect HIV-1 reservoirs and persistent infection. The impact of recreational drugs such as cannabis in HIV-1 patients remains understudied particularly in the African setting where HIV-1 is epidemic. A majority of the individuals infected with HIV-1 currently live in Africa where poverty, high HIV-1 infection rates and increasing rates of substance abuse co-exist. In Zambia, a sub-Saharan country in the heart of the HIV-1 epidemic, high prevalence cannabis use has been reported. Coupled with the high regional HIV-1 prevalence, the reports of substance abuse suggest that there is a need to determine how lifestyle choices, such as use of cannabis, might impact inflammation, persistent HIV-1 replication, or viral reservoirs in anti-retroviral therapy (ART) treated individuals. It has been shown that in aviremic ART treated individuals, low-level immune activation persists and contributes to viral persistence. Cannabinoids have been shown to modulate immune activation and inflammatory responses, and have demonstrated clinical impact in a number of chronic inflammatory disorders. The anti-inflammatory properties of cannabinoids could reduce the cellular activation that drives persistent low-level HIV-1 expression and therefore reduce the size of latent HIV pools. For these reasons, investigation of potential positive or negative effects of cannabis on inflammation, latent HIV reservoirs, or on HIV-1 replication in various tissues including the central nervous system is a highly relevant endeavor. We propose to leverage our existing HIV research infrastructure and expertise resulting from ongoing collaborations in Zambia for this study. We will collect and analyze autopsy cases from Zambian HIV-1 positive, cannabis users and controls to test the hypothesis that the anti-inflammatory properties of cannabis will lead to reduced persistent HIV-1 replication, in turn, leading to a reduction in the size and distribution of latent viral reservoirs. Our overall goals are to determine whether cannabis use correlates with reduce local immune activation, altered size and distribution of HIV-1 tissue reservoirs or reduced levels of persistent viral replication in those reservoirs. Our goal will be accomplished by addressing two specific aims: 1) Determine the prevalence of tissue pathology, the level of inflammation and immune activation in the brain and other potential tissue HIV-1 reservoirs, and define correlations with cannabis usage; 2) Determine whether cannabis use impacts the level of persistent viral replication or the size, distribution, and cellular composition of latent HIV-1 reservoirs in tissues. This study will lead to a greater understanding of the impact of cannabis usage and its effects on inflammation, on the distribution, the size and maintenance of HIV-1 reservoirs. The use of unique postmortem samples, supports the direct testing of a variety of concepts suggested from in vitro experimentation using tissue models and cell lines. This study may also provide useful information towards developing strategies to reduce the pool of latent reservoirs and possibly eliminate them.